Enhanced photovoltage and stability of perovskite photovoltaics enabled by a cyclohexylmethylammonium iodide-based 2D perovskite passivation layer

• Published in: Nanoscale 2021-09, Vol.13 (35), p.14915-14924
• Main Authors: Sun, Weihai, Zou, Jinjun, Wang, Xiaobing, Wang, Shibo, Du, Yitian, Cao, Fengxian, Zhang, Lan, Wu, Jihuai, Gao, Peng
• Format: Article
• Language: English
• Subjects: Capping; Efficiency; Energy conversion efficiency; Humidity; Ion migration; Open circuit voltage; Perovskites; Photovoltaic cells; Radiative recombination; Self-assembly; Solar cells; Stability
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d1nr03624f

Regardless of the impressive progress that perovskite solar cells (PSCs) have achieved, especially considering their power conversion efficiency (PCE) over 25%, traditional PSCs still contend with an inherent instability with exposure to humidity, which remains as a critical issue for the realization of commercial production. Herein, we proposed an effective pathway to relieve the instability of PSCs without sacrificing efficiency by introducing a 2D phase at the surface of the 3D perovskite film, based on a novel organic cyclohexylmethylammonium iodide (CMAI). The self-assembled thin 2D capping layer atop the 3D perovskite layer can not only reduce the ionic defects, but also serve as a protective barrier against moisture. Consequently, the champion device incorporating 2D perovskite capping layers delivered an open-circuit voltage ( V oc ) of 1.19 V, which contributes to an impressive PCE of 22.06% on account of the improved charge extraction and decreased non-radiative recombination. More importantly, an excellent long-term stability along with mitigated hysteresis was observed for the modified devices as a result of the suppressed ion migration and high humidity resistance of the 2D perovskite film. Our finding provides a comprehensive approach for simultaneously enhancing the efficiency and stability of PSCs through dimension engineering utilizing CMA-based 2D perovskite materials. Benefiting from an in situ formed 2D perovskite capping layer, a perovskite solar cell with a 3D/2D heterojunction structure exhibits a maximum power conversion efficiency of 22.06% and excellent moisture stability.